In medical applications, it is sometimes necessary to deliver fluid intravenously to a patient undergoing treatment. The fluid may be contained in a bag or other fluid reservoir, conveyed through a tube, and inserted into the patient's vein. At times, the amount of fluid conveyed to the patient must be controlled or regulated. In those instances where the fluid to the patient must be controlled, control modules, or pumps, have been used.
One control module, or pump, is described in U.S. Pat. No. 4,559,038. This pump controls the delivery of fluid from the reservoir to the patient. In the '038 patent, the fluid is in a bag held in a cassette immediately adjacent to the pump. The pump controls the amount of fluid to the patient by physically pressuring the tube from the bag to the patient, and restricting the volume of fluid allowed to flow to the patient. The pump includes a pump mechanism which engages the tube and squeezes the tube against a pressure plate of the cassette to effect pumping of fluid.
In the past, certain types of cassettes and pressure plates have been used to connect the pump to the tube. It is often desirable that access to the tube be limited to the medical professionals treating the patient. Because of this reason, and other reasons such as safety and cleanliness, the cassette is permanently attached to the pressure plate and the tube, with the reservoir contained securely in the cassette. When the fluid reservoir is empty, or the treatment to the patient completed, the cassette, reservoir, tube, and pressure plate are all thrown away. Disposing of the cassette contributes to waste and expense. There is a need for reusable cassettes that allow for replacement of a used reservoir and tube. There is also a need to limit access to the reservoir, such as in the case of hazardous drugs or controlled substances.